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Topic: Noise reduction

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List of noise topics

Image processing

Digital image processing

Signal processing

Noise

Transform coding

Image compression

Digital signal processing

Edge detection

Digital filter

Signal

Chroma subsampling

2D computer graphics

Computer vision

Bandwidth

	Noise Reduction: Digital Imaging: Glossary: Learn: Digital Photography Review
		The key to noise reduction is to reduce or eliminate the noise without deteriorating other aspects of the image.
		The noise in the blue sky of the original is very visible in the red channel.
		Bad noise reduction methods replace the noise by a wavy pattern in uniform surfaces, visible in the 1X crop.
	www.dpreview.com /learn/?/Glossary/Digital_Imaging/Noise_Reduction_01.htm (511 words)

	Noise Reduction
		All noise has a mechanical origin, which is to say it is the result of waves of pressure transmitted through air as the result of the mechanical movement of some object.
		Another source of noise is inherent in a motor’s relationship to both the mechanical and electrical effects of spinning parts moving through the air gap.
		Noise inherent in a motor generally cannot be "cured" by the motor installer.
	www.aosmithmotors.com /html/motorDoctor/noiseReduction.html (621 words)

	Noise reduction - Wikipedia, the free encyclopedia
		Noise reduction is the process of removing noise from a signal.
		Noise reduction techniques are conceptually very similar regardless of the signal being processed, however a priori knowledge of the characteristics of an expected signal can mean the implementations of these techniques vary greatly depending on the type of signal.
		In the case of photographic film and magnetic tape, noise (both visual and aural) is introduced due to the grain structure of the medium.
	en.wikipedia.org /wiki/Noise_reduction (1006 words)

	FiberBrace Structural Wall Sheathing Benefits: Noise Absorption
		Noise is simply sound waves, and sound waves are air pressure fluctuations or vibrations that radiate from a source like the ripples in a pond.
		If the noise source is expected to be inside the home, from a child’s room possibly, it can be separated from the rest of the home by less sensitive areas like bathrooms, hallways or closets.
		Depending on the severity of the noise to be managed, the stage of the structure’s construction cycle initiated and the budget available, the amount of work and construction complexity may be limited or involved.
	www.temple.com /fbbuild/noise.html (1655 words)

	Noise reduction
		It is assumed that the signal is distorted by a wide-band, stationary, additive noise, the noise estimate is the same during the analysis and the restoration and the phase is the same in the original and restored signal.
		To obtain the noise estimate, the part of the recording containing only noise that precedes the part containing speech signal should be analysed (the length of the analysed fragment should be at least 300 ms).
		During the restoration, the reduction coefficients should be reduced in bands where the speech signal becomes distorted and increased in the bands where noise level is too high.
	sound.eti.pg.gda.pl /denoise/noise.html (550 words)

	Noise Reduction troubleshooting and guidelines (Audition 2.0) - Support Knowledgebase (Site not responding. Last check: 2007-11-01)
		Noise reduction, at its most basic level, is a series of filters which allow you to remove specific frequencies of audio, that is, the frequencies at which the noise occurs.
		The Noise Reduction effect captures a noise reduction profile from your file then uses this profile to subtract the noise from the rest of the signal based on the settings you choose.
		The Noise Reduction effect works by capturing a noise reduction profile from your file then using this profile to "subtract" the noise from the rest of the signal based on the settings you choose.
	www.adobe.com /support/techdocs/332261.html (2975 words)

	RPA : Noise Reduction With Asphalt-Rubber (Site not responding. Last check: 2007-11-01)
		A significant noise reduction of 3 to 5 dB with no trucks, and 2 to 3 dB reduction with five percent trucks, were recorded, a 50- to 75-percent noise reduction.
		Three to ten dB reductions with speeds of 35 mph (60 km) to 60 mph (100 km) were recorded, representing 50- to 90-percent reduction in noise levels.
		Noise reduction values of 6 dB, or 75-percent noise reductions were recorded.
	www.rubberpavements.org /library/noisereduction.asp (1280 words)

	Noise Reduction (Site not responding. Last check: 2007-11-01)
		Noise impact of aircraft operations is already constraining the air transportation system through curfews, noise budgets, and slot restrictions.
		Noise issues are also inhibiting expansion or construction of new facilities.
		Increasing stringency in aircraft noise standards has mandated phase-out of stage 2 airplanes by the year 2000, and the number of airports affected by local noise restrictions has grown from 119 airports in 1980 to 595 in 2000 worldwide.
	www.hq.nasa.gov /office/aero/events/chicago/noise.htm (292 words)

	effective noise reduction
		The amount of noise reduction is dependent on the approximate signal-to-noise ratio for each channel and the noise reduction setting.
		The noise level is fixed at 65 dB(A) with the level of the sentences adjusted until the patient repeats the sentences correctly 50% of the time.
		In contrast, the noise reduction algorithm is insensitive to spatial separation and/or directionality, i.e.
	www.audiologyonline.com /articles/pf_article_detail.asp?article_id=290 (2189 words)

	Helicopter noise reduction - Wikipedia, the free encyclopedia
		Loading noise is an aerodynamic adverse effect due to the acceleration of the force distribution on the air around the rotor blade due to the blade passing through it, and is directed primarily below the rotor.
		While most noise from a helicopter is generated by the main rotor, the tail rotor is a significant source of noise for observers relatively close to the helicopter, where the higher-frequency noise of the tail rotor has not yet been attenuated by the atmosphere.
		Tail rotor noise is particularly annoying to the human listener due to its higher frequency (as compared to the main rotor) which places it directly in the band in which the human ear is most sensitive.
	en.wikipedia.org /wiki/Helicopter_noise_reduction (801 words)

	Noise Reduction Hearing Aids
		In this instance, the nature of the noise doesn't matter, whether it is considered "desirable," i.e., music (and the selection is irrelevant), or undesirable sounds such as the racket produced by a pneumatic drill.
		While noise can vary in an almost infinite number of ways, we know that the nature of speech is syllabic, with relatively intense vowels followed by weaker consonants and pauses.
		But this is not the same as the promise inherent in the label "digital noise reduction," that is, the technical capability of some miracle hearing aid to virtually eliminate all competing sounds when listening to speech in a noisy situation.
	www.hearingresearch.org /Dr.Ross/NoiseReductionHAs.htm (2432 words)

	[No title] (Site not responding. Last check: 2007-11-01)
		Noise reduction is a subject to research in many different fields.
		The goal of the noise reduction is to reduce the noise level without distorting the speech, thus reduce the stress on the listener and - ideally - increase intelligibility.
		A fundamental requirement for most mono sensor systems is that speech and noise are additive and results of uncorrelated statistical processes, and that the spectral characteristics of the noise changes markedly slower than those of the speech.
	www.ind.rwth-aachen.de /research/noise_reduction.html (3079 words)

	Noise: Digital Imaging: Glossary: Learn: Digital Photography Review
		Noise in digital images is most visible in uniform surfaces (such as blue skies and shadows) as monochromatic grain, similar to film grain (luminance noise) and/or as colored waves (color noise).
		Noise also increases as pixel size decreases, which is why digital compact cameras generate much noisier images than digital SLRs.
		As explained in the noise reduction topic, long exposure noise is much less visible in the latest digital cameras.
	www.dpreview.com /learn/?/Glossary/Digital_Imaging/Noise_01.htm (451 words)

	Noise Reduction By Image Averaging
		Two averaged images usually produce noise comparable to an ISO setting which is half as sensitive, so two averaged images taken at ISO 400 are comparable to one image taken at ISO 200, and so on.
		In general, magnitude of noise fluctuation drops by the square root of the number of images averaged, so you need to average 4 images in order to cut the magnitude in half.
		Image averaging does not work on images which suffer from banding noise or fixed pattern noise.
	www.cambridgeincolour.com /tutorials/noise-reduction.htm (1232 words)

	Singer Safety Company - Noise Reduction Principles
		An energy source produces noise as a radiating sound pressure wave which moves through the air in all directions.
		The most effective, economical and flexible method of noise reduction is usually the construction of a barrier (or enclosure) between the noise source and the receiver.
		It is important to consider the use of sound absorbing material on the inside surfaces of a noise barrier, especially when a full or partial enclosure is being designed.
	www.singersafety.com /noise_reduction.htm (358 words)

	Window Noise Reduction Comparison
		Soundproof Windows can reduce the current noise levels by 95% or by 75%, and both statements will be true: one is the instrument measurement, while the other is the perceived noise reduction.
		Additionally, depending on actual noise levels, the noise reduction may be perceived as 100%.
		In the rare events where the noise levels are really extreme or the sensitivity very high, we can install a third window and absolutely stop the problem - reducing the perceived noise levels beyond 95%.
	www.soundproofwindows.com /comparison.html (301 words)

	Thayer School - Research in Active Noise Reduction (Site not responding. Last check: 2007-11-01)
		High environmental noise levels constitute a serious threat to the hearing of factory workers, emergency personnel, military personnel, and others who work for long periods in noisy environments.
		Basic research in hearing protection and enhanced communication in high-intensity noise environments is being conducted jointly by Thayer School and Dartmouth Medical School using active noise reduction (ANR)—a.k.a., active noise control, or active noise cancellation.
		This approach is to measure the incident acoustic field and, through adaptive processing, introduce the interfering noise field by a secondary speaker at or near the receiver or ear.
	engineering.dartmouth.edu /thayer/research/noisereduce.html (456 words)

	HQV - Hollywood Quality Video Processing for HD : Noise Reduction (Video)
		Not only does noise get introduced during post-production editing or the final stage of video compression, but it is also present at the source in the form of film grain or imaging-sensor noise.
		The simplest approach to noise reduction is to use a spatial filter that removes high-frequency data.
		In static areas, the strength of noise reduction is determined on a per-pixel basis, depending on the level of noise in the surrounding pixels as well as in previous frames, allowing the filter to adapt to the amount of noise in the image at any given time.
	www.hqv.com /technology/index1/noise_reduction.cfm?CFID=&CFTOKEN=1b471c5427bd444e-CE269D43-7E90-E2A3-BD6643EC062A7036 (407 words)

	Port of Seattle: Noise: Overview
		Read about Noise Abatement for information on how the airport reduces the noise produced by aircraft while on the ground, during takeoffs and landings and during flights over populated areas.
		Our Noise Remedy programs are designed to significantly reduce aircraft noise that people hear in their homes and in the classroom.
		The ultimate goal of noise compatibility planning is to reduce existing non-compatible land uses around airports and prevent the introduction of additional non-compatible land uses through the cooperative efforts of all those involved.
	www.portseattle.org /community/environment/noise.shtml (395 words)

	Digital Darkroom @ The Light's Right Studio
		TLR Digital Noise Reduction is a set of Photoshop actions for reducing noise in digital images.
		Reduction of chroma noise is another sophisticated feature of the TLR Digital Noise Reduction actions.
		Three progressive strengths of chroma noise reduction are applied by making a duplicate image that is converted to Lab mode where chroma noise can be more effectively removed (and with less softening of image details).
	www.thelightsrightstudio.com /TLRDigitalNoiseReduction.htm (638 words)

	Effective Noise Reduction
		Since this form of noise reduction needs to 'actively' seek and subtract the spectrum of the noise, the system needs a method to determine the difference between speech and noise.
		The steady-state noise used to test the noise reduction algorithm is the same HINT masker used in many directional microphone investigations.
		In contrast, the noise reduction algorithm is insensitive to spatial separation and/or directionality, i.e.
	www.healthyhearing.com /library/article_content.asp?article_id=108 (2256 words)

	NASA - Quiet Aircraft facts
		Increases in air traffic and growth in populations that surround airports are resulting in a noise impact on a larger percentage of the community and a stronger desire to reduce the noise around airports.
		Theoretical understanding of jet noise is used to develop ideas for noise reduction concepts that are tested in model scale.
		A second approach uses the theoretical understanding of fan noise to develop a succession of ideas for testing, with each test providing both data upon which the computer codes are verified and results upon which the next test might be built.
	www.nasa.gov /centers/glenn/about/fs03grc.html (1511 words)

	Bona Fide Reviews - Noise Cancelling or Noise Reduction When It Comes to Headphones Article
		Noise canceling headphones tend to work best for constant sounds like lawn mowers and appliances but they allow in intermittent sounds, such as conversation or a ringing phone, so you are not totally isolated.
		Noise cancellation headphones attempt to block sound by sampling the outside sound and then producing an equal but opposite sound - sometimes the approximation of sound can be difficult.
		He uses Extreme Isolation Noise Reduction Headphones (http://www.quietheadphones.com) in his recording studio as well as his office during work to block out distractions.
	www.bonafidereviews.com /article.php?id=117 (582 words)

	Noise Reduction Headphones / Noise Cancelling Headphones : EX29 Extreme Isolation Headphones
		This form of noise cancellation is called active cancellation and has gotten a great deal of attention due to the complicated technology used.
		Active noise cancellation is an effective way to block sound, but it tends to produce a hissing, swooshing sound inside the ear cups.
		If, however, you are unsatisfied with these noise cancelling - canceling reduction headphones for any reason, simply send them back to Direct Sound Headphones LLC within 60 days in good condition and in the original packaging, and you will promptly receive a full refund of the purchase price.
	www.quietheadphones.com (1257 words)

	O'Reilly -- Seven Steps to Noise-Free Digital Audio
		Noise levels are typically higher in analog recordings, but some noise exists in all digital recordings as well.
		Distortion is similar to noise, but there is a key difference: Noise is something that’s introduced to the signal from outside, such as hum, whereas distortion is a modification of the signal itself.
		Noise removal tools can be effective when applied correctly, but if you process an entire file with settings that are aggressive enough to get rid of all the noise, chances are you’ll also get rid of a lot of music, especially “spiky” sounds, like cymbals and snare drum hits.
	digitalmedia.oreilly.com /2005/06/22/noise.html (3060 words)

	Noise Reduction (Site not responding. Last check: 2007-11-01)
		If the noise is not masked by loud passages then one may hear the compander “pumping” or “breathing”.
		So the noise of a two track recording is 3 db higher than that of a mono recording, while the inherent noise of four tracks is 3 db higher than two, and so on.
		Luckily there are very effective noise reduction techniques available for use with analog tape which rival the signal to noise specifications of digital recordings.
	www.sfu.ca /sca/Manuals/ZAAPf/n/noise_reduction.html (303 words)

	Noise Reduction Tool Comparison
		Chroma noise is visible as random red and blue pixels and is usually less obvious both on screen and printed.
		Removing luminance noise reduces the sharpness of the image and removing the chroma noise damages some of the correct color.
		So noise reduction is a balance between how much softness and color damage you are willing to accept vs. how much noise you want to remove.
	www.michaelalmond.com /Articles/noise.htm (422 words)

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